Hey guys, I'm just wondering what all the higher hp guys are running for crank case breathers. I put a brand new Dart 427 in the car this past year. The motor has developed several leaks from the pan after 300 miles of driving. I took it out the other day and made a very short hit on 27psi. Got home and the front seal is leaking now. The dip stick has not blown out.

Plugs look great.

I'm currently running a -10 from each valve cover to a catch can. I ordered a manometer to check the crank case pressure, but figured I'd see what everyone else is running, too.

The motor was built by a well known LS builder.

I have noticed some oil making it's way past the compressor and into the intercooler. I've also noticed an odd smell coming from the turbo drain line...I'm not sure if it's burnt oil or possibly exhaust smell mixed with oil. I pulled one of the oil pan bolts and re-torqued it in a futile attempt to stop the leak..the bolt had that same odd, burnt smell.

Your ideas would be appreciated.

Thanks!

 

I like to run big lines on everything. Minimum 12an. 16an if you can.

 

What is your oil temp running at? I know the burnt smell you mention. Usually comes from cooking the oil or total abuse and not changing. Shows up under the bolts like you mention.

 

Oil temp is one thing I don't monitor, although I know I probably should. Never had a problem with it on my old motor. Pressure stays around 42psi when hot...never dips under. Running Vr1 20-50. I've been very easy on this motor so far, no passes yet, not even any dyno pulls. Makes me think the oil in the turbo center section is getting backed up or something.

 

I do have an unused return drain port on the other side of the oil pan...I could run a breather to that, too.

 

I would probably leave that covered and vent both valve covers and you could vent the valley cover as well. Size would be depending on the intake manifold you are running

 

Yeah, I have the vented valley cover off my old motor. I could put that on or fab something up. Not a lot of restriction as I'm running a Vic Jr. intake.

 

I run I want to say -10 off each valve cover to a large catch can vented to atmosphere on 346 cubes up to 21.5 lbs. without issue.
I'd be looking at least -12 or larger, 427 cubes is a lot of pumping action within the crankcase combined with nearly 30 lbs. of boost is asking a lot of -10 imo.
I'm with @jayyyw on this, nothing bad can come from oversizing crankcase ventilation but going to small well......

 

Ditch the vented stuff, save that for the drag racing only guys. Street rigs should get actual PCV.
I use a single 3/4" line with a vertical 6" section off the valve cover to help oil separate, to a large catch can, and then to just behind the air filter. I pull vacuum on the crankcase in all conditions(heavy vacuum in boost, as the PCV is referenced to how much air the engine consumes) and never even gotten oil in the catch can. Zero oil in intake. Proper baffle in the valve cover helps.
Zero oil leaks for lots of abusive street miles. Oil always looks great.

 

I run a 12an line off each valve cover without issue. No oil in my can or in my intake manifold zero, oil leaks. 25 psi of boost. Keeping it simple is usually the best

 

Same here, in fact I've only emptied my can once the entire time I've owned the car lol.
Never had an issue smells or anything.
Put the can up in the front of the car and you'll have no issues with smells.

 

Same same. But there's some guys that will die on that PCV hill. I'm gonna be switching to two catch cans instead of having lines routed from one side to the other

 

I ran a MM PCV can on my last car and it was great, but I had to add a -12AN vent to keep my dipstick in.
That was just a little 7875, LS1 deal on 14 lbs. so it didn't require much.
There's a reason you don't see big power guys running PCV cans after a certain point.

 

You can still run PCV and a can to help with blowby smell and clean up the crankcase while in vacuum while having large valve cover vents. I run dual -10's on the covers and my ls6 valley plate to the PCV with a closed catch can, but you would want to be speed density in this case or you will suck in unmetered air through the vents.

 

What size turbo? 1500HP?

Sounds like you need -12 to -16, two of them off the valve covers.

I'm running two -10 but I'm only making 900-1000.

 

Let's not forget about exhaust evac system either.
Run a large vacuum line -12/-16 to the turbo down pipe and let the exhaust evac the crank case under WOT then run a PCV can for when not at WOT.
Maybe the best of both worlds?

 

I'd just like to tell you guys what I'm running on my 6L turbo truck, it's making around 800 crank. -6 lines of each valve cover , drivers side cover I drilled out the fixed orifice to the biggest bit I could get in there , Don't remember the size. Added a gen 1 type pcv valve using various small pieces of hose. Home made catch can with 2 check valves ( wrecking yard brake booster sourced ) under boost both valve covers see a bit of vacuum from air filter restriction pre turbo , normal driving is a basic pcv system- non vented. I've had friends get tickets for open breathers so not doing that . Only intended to run about 10 lbs so I figured I would try this at the start change if needed, now running up to 17.5 lbs with no issues with leaks or dipstick. This was a 180k mile engine that I didn't gap rings on , similar engine had about .023" gap on top ring. Thinking the fairly tight ring gap and filter restriction vacuum to both covers is why it works . Certainly not any comparison to the OPs combination but he could have a blowby issue but if not the exhaust evac idea should certainly help . I have not even tried to measure the pre turbo vacuum mostly because it works and can't really be bothered to do it

 

I appreciate all the feedback, guys. I ran a much more restrictive breather setup on my old 385" motor and same turbo- 94mm billet gt55. Never had any issues. I haven't had the car on the dyno yet, but I'm assuming the motor is a conservative 630hp n/a. At 27lbs...it should be over 1700 crank, theoretically.

I did discover the catch can filter was totally saturated with oily water vapor, as I've had two rags wrapped around it to stop the oil from getting everywhere. I've since removed the rags, and it's definitely breathing better. I'm not sure if that would have been enough to cause leaks or not.

Unfortunately, I'll be winterizing the car in a few days as they already started salting the roads. I'll make sure and update this thread next spring.